Sleep is important for healing and survival of critical illness, as far as quantitative and qualitative sleep deprivation can have negative consequences on a physiologic function, particularly the immune mechanism, as well as psychological well-being [1].

Patients' perception of intensive care is very different depending on the study. To illustrate, Simini reported frequent feelings such as 'pain, noise, sleep deprivation, thirst, hunger, fear, anxiety, and isolation' [2], but Granja and colleagues showed that 38% of patients did not remember at all their intensive care unit (ICU) stay and that 93% described the ICU environment as friendly and calm [3]. These authors also reported contrasting results: Simini reported that 61% of patients had sleep deprivation in the ICU, whereas sleep was described as being good and sufficient by 73% of patients in the study by Granja and colleagues.

We explored the memorization of sleep disturbances during an ICU stay and then evaluated the quality of sleep reported by patients after critical care.

A telephone interview including a random sample of 60 patients admitted to our ICU was performed 6 to 12 months after their discharge. Conventional intensive care variables were recorded from the ICU database and sleep disturbances were evaluated using the Basic Nordic Sleep Questionnaire [4]. Two nonvalidated questions were also analyzed: one estimated the quality of sleep in the ICU, while the other compared the quality of sleep before and after a stay in the ICU.

Among 53 responding patients, 47% remembered sleep disturbances in the ICU - among these sleep-disturbed patients, 43% still declared a decreased long-term quality of sleep. In addition, 30% of patients reported a worse quality of sleep after their ICU stay than before admission. No relation was found when we assessed the possible effects of ICU variables on sleeping patterns during critical illness.

Sleep disturbances were described in one-half of the patients during their ICU stay. We noticed that one-third of the group declared having a poorer quality of sleep a long time after their discharge from the ICU. Our results differ from those of another study where the prevalence of self-reported quality of sleep did not change from the pre-ICU period to the post-ICU period and where the results did not incriminate the ICU stay in a long-term worse quality of sleep but did incriminate concurrent diseases [5]. The high self-reported prevalence of sleep disturbances, however, reveals the necessity for systematic protocols to improve sleep quality in the ICU.